Broadband signalling

ABSTRACT

A method and means for generating a connection correlation identifier (CCID) in multiconnection calls over broadband networks is provided. Signalling with the CCID takes part at the users interface. The connection correlation identifier coordinates the individual connections with the respective multiconnection call. The CCID includes two parts, and originating part (OCCID) and a destination part (DCCID), where the OCCID is generated at the calling party and where the DCCID is generated at the called party.

TECHNICAL FIELD OF THE INVENTION AND DESCRIPTION OF RELATED ART

When using a broadband network, different types of calls could be setup. For example B-ISDN standards offers both ordinary point to pointcalls between two users, but also point to multipoint calls. Newsignaling standards are continuously set by ITU-T concerning the ATMenvironment. In the closest future new standards regarding point topoint multiconnection calls will be set. The need for point to pointmulticonnection calls occurs when several connections have to beestablished within one single call between two users. Multimedia is oneapplication where this technique is applicable, for example to sendvideo on one channel, speech on a second and data on a third channel.Video on demand could be another adequate application.

Multiconnection calls per se are already known as a service in B-ISDN.The provision of multiconnection calls requires special parameters, forexample the originating Call Identifier (OCID) and the Destination CallIdentifier (DCID). The OCID is assigned by an originating local exchangeprior to establishment of a multiconnection call. It is used to identifythe call association between originating and destination localexchanges. The DCID identifies the call association at the receiving endand is created at the destination exchange. The first Originating CallIdentifier value received is reflected as the Destination CallIdentifier value. The call identifiers at the originating anddestination exchanges remain constant as long as a signallingassociation belonging to a multiconnection call is present. The callidentifiers are independently assigned by each of the originating anddestination exchanges concerned, A and B, enabling each exchange touniquely identify the signalling associations belonging to amulticonnection call.

The originating call identifier A is assigned by the originatingexchange A, when sending the first message for the first signallingassociation belonging to a multiconnection call, it is used to identifythe signalling associations belonging to a multiconnection call at theoriginating exchange A.

The originating call identifier B is assigned by the destinationexchange B, when receiving the first message for the first signallingassociation belonging to a multiconnection call, it is used to identifythe signalling associations belonging to a multiconnection call at thedestination exchange B.

The destination call ID A equals the originating call ID A, and thedestination call ID B equals the originating call ID B.

The first initial address message of a signalling association belongingto a multiconnection call shall contain the OCID—A.

The succeding IAM messages relative to the same multiconnection callshall contain the DCIB-B.

In the destination exchange, the first backward message sent after theInk message for the first connection shall contain the OCID-B and theDCID-A.

The OCID and DCID parameters are only processed by the originating andthe destination exchanges. These parameters convey transparently throughall intermediate exchanges in the B-ISDN network and have no U;Isignificance. The signalling with the OCID and DCID according to what isdescribed above is performed in the higher B-ISDN layers and is relevantto the ATM NNI (Network Node Interface), more specific according to the.B-ISUP protocol shown in FIG. 1. As also can be seen in the figure, theB-ISUP only handles the signalling on the ATM NNI level where it servesto guarantee unique connection identifiers between originating anddestination exchange. The B-ISUP operates over the Message TransferProtocol 3 (MTP3). This allows B-ISDN to operate directly over ATMnetworks. The series of ITU-T Recommendations Q.2761 through Q.2764specify the B-ISUP protocol.

The invention on the other hand relates to broadband signalling at theuser interface. (see FIG. 1a, 1 b and 1 c) i.e at the ATM UNI-level(User Network Interface) where a need of a Connection CorrelationIdentifier (CCID) has been identified, in order to coordinate theindividual connections with the respective multiconnection call. This isneeded because in a private network it will be possible to route theindividual connections of the call differently.

The B-ISUP protocol for multiconnection calls has to support thetransfer of the values of the Connection correlation identifier.

The mechanism which will be further described is similar to thesignalling according to the B-ISUP protocol. By using a similarmechanism as the B-ISUP at the ATM UNI, additional non-expextedadvantages, which will be described, are obtained.

BRIEF DESCRIPTION OF THE DRAWINGS

The objects and advantages of the invention will be understood byreading the detailed description in conjunction with the drawings, inwhich:

FIGS. 1A-1C illustrate the use of broadband signaling at the userinterface;

FIG. 2 illustrates the establishment of a multiconnection call accordingto an embodiment of the invention;

FIG. 3 illustrates the establishment of a multiconnection call accordingto another embodiment of the invention;

FIG. 4 illustrates the establishment of two multiconnection callsaccording to an embodiment of the invention; and

FIG. 5 illustrates the establishment of two multiconnection callsaccording to another embodiment of the invention.

DESCRIPTION OF THE INVENTION

This invention further relates to how to generate and use the ConnectionCorrelation identifier for point to point multiconnection calls andproposes that the Connection Correlation identifier shall be composed oftwo parts, an originating part (OCCID) and a destination part (DCCID).The Connection Correlation identifier is always generated by the callingand called parties during call establishment and is used as mentionedabove for broadband signalling at the user interface.

When the coordination process receives a new request to set up aconnection it has to find out whether this new connection belongs to acompletely new call or to an already active call with already zero ormore connections. A call can consequently be regarded as active evenwhen it has zero connections. This is possible due to something calledprenegotiation which precedes connection setups. During thisprenegotiation the calling party exchanges information with the calledparty, if he e.g is ready and able to accept a multiparty call. However,the coordination process has to be done within the network at theoriginating and destination interface as well as by both users, becauseeach of them may receive requests for additional connections.

If two reference points at the originating and destination interface aredefined as Sb and Tb, a scenario is possible where the points coincide.This scenario occurs when the calling party directly accesses a publicATM network and does not connect to any private switches in between (seeFIG. 1b). Then the task mentioned above could be solved by usingseparate messages for establishing the call and additional connections.But for all other scenarios, where at least one private network isaccessed, this solution does not work, because within the privatenetwork the individual connections can be routed differently. Thus, forexample, the second connection may enter (or leave) the public networkvia another access. As a consequence of this it was decided by the ITU-Tto always use an already known predefined signalling message calledSETUP and to introduce the Connection correlation identifier. This leadsto a simplification of the protocol by increasing the re-use of theITU-T recommendation Q.2931 (se FIG. 1), which specifies the B-ISDNsignalling on the ATM UNI, and by aiming at one solution (to be agreed)for both types of reference points.

To use and implement the signalling with the CCID according to theinvention, the following description is valid and functioning for bothinterfaces, the scenario with the coincident Sb and Tb reference pointand also for the Tb reference point for interworking with private ISDNs:

The Connection correlation identifier (CCID) shall, as mentioned, becomposed of two parts, an originating part (OCCID), and a destinationpart (DCCID). Both values shall represent together a global identifierwhich has user-to-user significance.

The CCID shall always be created in conjunction with call establishment.The mechanism is similar to the one used for the B-ISUP to guaranteeunique connection identifiers (OCID-A, DCID-A, OCID-B, DCID-B) betweenoriginating and destination exchange.

Generation of the CCID, if the call is established together with thefirst connection:

The calling user assigns a OCCID and includes it in the SETUP messagetogether with a dummy value for the DCCID. Due to the dummy DCCID, thenetwork at the originating interface recognize that the requestedconnection belongs to a new call. The content of the CCID shall betransferred unmodified through the network. At the destination interfacethe network includes the CCID without any modifications into the SETUPmessage, which is then sent towards the called user.

Upon receiving the SETUP message with the dummy DCCID, the called userrecognizes that the requested connection shall belong to a new call. Thecalled user assigns a DCCID, which will be sent back in the CONNECTmessage together with the unmodified OCCID. The CONNECT message is alsoa predefined signalling message.

Thus the network at the destination interface receives the completelycomposed CCID, stores it for later coordination purposes and forwards itto the originating interface. There the network stores it again forlater coorrdination purposes and also transfers it in the CONNECTmessage towards the calling user.

Handling of additional error conditions:

If the network or the called user receives a SETUP message with a dummyvalue for the OCCID, the message shall be ignored. If the network or thecalling user receives a CONNECT message with a dummy value for theDCCID, then clearing shall be invoked.

Generation of the CCID, if the call is established with prenegotiation:

The same principles as if the call is established together with thefirst connection apply. In addition the CCID may also be included in theFACILITY message, which also is a predefined signalling message that isused during the prenegotiation.

The conceivable possibilities for the transfer of the CCID are tointroduce an additional information element in the FACILITY message orto extend the prenegotiation operation.

Usage of the CCID, if additional connections are requested:

Both, calling user and called user, can request simultaneously severaladditional connection requests (i.e become connection owner). The SETUPmessages used for this shall include the CCID.

Upon receiving the SETUP message with a complete CCID (without dummyvalues) the network shall register it if not already known (this ispossible at the pure Tb reference point). Then the connection request istransferred through the B-ISDN together with the CCID. At the receivingside the network shall also register the CCID, if unknown. Then the CCIDshall be sent within the SETUP message to the non-connection owner. Thenon-connection owner shall validate the CCID before accepting a requestfor the additional connection.

Handling of additional error conditions:

If the non-connection owner receives from the network a SETUP messagewith an unknown CCID, then the message shall be ignored. (Note: in caseof coincident Sb and Tb reference point an invalid CCID could also berecognized earlier. But it is recommended to use the procedure indicatdeabove which works with all configurations of the reference points.)

The following paragraphs discloses four different scenarios which canoccur within the embodiment of the invention. They are all illustratedwith drawings:

FIG. 2 depicts a succesful establishment of a multiconnection callwithout different routing in the private network and is valid for bothtypes of reference points. It shows that it is the called and thecalling party that creates the OCCID and the DCCID and that curing thesetup of the second connection the complete CCID is set before theconnecting procedure so as for the system to know that it is a multiplecall that correlates to the first call.

FIG. 3 depicts a succesful establishment of a multiconnection call withdifferent routing in the private network and shows that the terminalsare able to correlate the two connections to the same call.

FIG. 4 depicts an establishment of two multiconnection calls. In theexample two users request for a multiconnection call to the samedestination. Both terminals generate the same OCCID for themulticonnection call. The destination user may not generate the sameDCCID again. So for each multiconnection call a unique DCCID is created.The same situation applies also if on the left hand the two terminalsare connected to the same exchange.

FIG. 5 depicts multiconnections call requests for different destinationsindicating the same OCCID. In the example two user request for amulticonnection call towards different called users. When receiving thecall request, each called user may generate the same DCCID without amix-up of the calls.

To conclude, the invention aims to enable the coordination processes toassign connections to the right call by the use of a Connectioncorrelation identifier composed of two parts, one provided from thecalling user, and one provided from the called user. It will also enablethe coordination process of the network to decide if a new call has tobe established (just because not both parts of the Connectioncorrelation identifier are available).

The fact that the identifier has an originating and terminating part, nouser can achieve a situation of having two multiconnection calls withidentical values of the Connection correlation identifier. It shall benoted, that from the network point of view, uniqueness is not required.

Another advantage that is obtained by using the invention is that thereis no need to introduce different procedures for the two types ofreference points, the invention handles the coincident Sb and Tbreference point as well as the Tb reference point for interworking withprivate ISDN:s

A liason statement has to be written to achieve that the CCID can betransformed transparently through the B-ISDN.

What is claimed is:
 1. A method for signalling in broadband networks atthe user interface, the method comprising: requesting establishment of acall; exchanging information between a calling party and a called party;and generating a connection correlation identifier (CCID), wherein theconnection correlation identifier: coordinates the individualconnections with the respective multiconnection call; is generated bythe calling and called parties during call establishment, and iscomposed of two parts, an originating part and a destination part.
 2. Amethod for signalling in broadband networks according to claim 1,wherein the step of generating the connection correlation identifierfurther comprises: assigning, by the calling party, an Originatingconnection correlation identifier (OCCID) during a call establishmenttogether with the setup of the first connection of a multiconnectioncall or together with the prenegotiation and assigning the Destinationconnection correlation identifier (DCCID) a dummy value, and assigningby the called party a valid DCCID value if it receives a dummy value, tocomplete the CCID.
 3. A method for signalling in broadband networksaccording to claim 2, wherein the calling and called party use thecomplete CCID, that was created during the setup of the first connectionof a multiconnection call or during the prenegotiation, in all otherconnections of the same multiconnection call.
 4. A method for signallingin broadband networks according to claim 1, wherein the originating partof the connection correlation identifier is assigned by the callingparty and the destination part is assigned by the called party.
 5. Amethod for signalling in broadband networks according to claim 4,wherein the connection correlation identifier is generated when the callis established with the first connection.
 6. A method for signalling inbroadband networks according to claim 4, wherein the connectioncorrelation identifier is generated when the call is established withthe prenegotiation.
 7. A system for signalling in broadband networks atthe user interface, the system comprising: means for requesting aconnection setup; means for exchanging information between a callingparty and a called party; and means for generating a Connectioncorrelation identifier (CCID), wherein said connection correlationidentifier: coordinates the individual connections with the respectivemulticonnection call is generated by the calling and called partiesduring call establishment, and is composed of two parts, an originatingpart and a destination part.